Transit time tube with a coil-like delay line

ABSTRACT

A transit time tube includes a helical delay line which is held at a determined pressure inside a tubular component forming part of the vacuum sleeve of the tube between support rods consisting of insulating material which extend along the delay line. At least one of the support rods is pressed by at least one ram onto the delay line, which ram extends through a side opening in the tube and is fixed to the tube in the vacuum tight manner. In producing the tube a lateral opening is bored into the sleeve to receive the ram and the walls of the opening are metallized. Then the delay line is placed between support rods which are inserted into the sleeve and fixed against the latter. Subsequently, a further support rod is placed between the delay line and the lateral opening and is pressed onto the delay line with a ram under pressure, which ram extends through the lateral opening and is likewise metallized on its periphery in the region of the opening. Next the sleeve and ram are soldered together in a furnace. The portion of the ram which extends beyond the outer surface of the sleeve may be ground off, or the same may extend through the external tube component, such as the magnet system, and be affixed to a heat radiator.

United States Patent [191 Hinckeldey et al.

[ July 15, 1975 1 TRANSIT TIME TUBE WITH A COIL-LIKE DELAY LINE [75] Inventors: Arno Hinckeldey; Helmut Katz,

both of Munich, Germany [73] Assignee: Siemens Aktiengesellschaft, Berlin & Munich, Germany 22 Filed: June 3,1974

2| Appl.No.:475,782

[30] Foreign Application Priority Data June 7, I973 Germany 2329l53 [52] U.S. Cl 333/31 A; 29/600; 315/35, 333/95 R [51] Int. Cl HOlp 9/02; HOlj 25/42 [58] Field of Search 333/31 A, 95 R; 315/35; 29/2513, 25.14.2515, 600

[56] Relerences Cited UNITED STATES PATENTS 172L614 9/l966 Scott. sis/3.5 3,72l,6l5 9/1966 Washburn. Jr INS/3.5

FOREIGN PATENTS OR APPLICATIONS l,243,282 6/1967 Germany 3l5/3.5

Primary Examiner-James W. Lawrence Assistant ExaminerMarvin Nussbaum Attorney, Agent, or FirmHill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson 5 7 ABSTRACT A transit time tube includes a helical delay line which is held at a determined pressure inside a tubular component forming part of the vacuum sleeve of the tube between support rods consisting of insulating material which extend along the delay line. At least one of the support rods is pressed by at least one ram onto the delay line, which ram extends through a side opening in the tube and is fixed to the tube in the vacuum tight manner. In producing the tube a lateral opening is bored into the sleeve to receive the ram and the walls of the opening are metallized. Then the delay line is placed between support rods which are inserted into the sleeve and fixed against the latter. Subsequently, a further support rod is placed between the delay line and the lateral opening and is pressed onto the delay line with a ram under pressure, which ram extends through the lateral opening and is likewise metallized on its periphery in the region of the opening. Next the sleeve and ram are soldered together in a furnace. The portion of the ram which extends beyond the outer surface of the sleeve may be ground ofi, or the same may extend through the external tube component, such as the magnet system, and be afiixed to a heat radiator.

8 Claims, 1 Drawing Figure TRANSIT TIME TUBE WITH A COIL-LIKE DELAY LINE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a transit time tube having a helical delay line which is supported at a predetermined pressure within a tubular component, forming part ofthe vacuum sleeve of the tube, between support rods consisting of insulating material which extend along the delay line.

2. Description of the Prior Art The life duration and load capacity of the type of tube described herein are fundamentally dependent upon whether it is possible to discharge to a sufficient extent the heat developed in the helical delay line during operation. This is governed by the nature of the heat transfer between the delay line and its electrically insulating support rods. Therefore, in particular, the coil holder should be subjected to a pressure which is of a sufficiently great specific magnitude and which remains reliably constant over as long a period as possible.

A helix or coil holder exhibiting a predetermined bearing pressure is known from the German published application DAS 1,243,282, in which, in the region of the coil, the vacuum sleeve consists of a number of separate metallic wall components, which number corresponds to the number of support rods, the wall components being arranged parallel to one another and delimiting, between one another, continuous longitudinal slots into which project members in the order of support rods which are applied to adjacent slotted inner edges of the metallic wall components. The longitudinal slots are sealed in full and in vacuum tight fashion from the exterior by means of further metallic components. The pressure is formed by the heat shrinkage of the vacuum sleeve in that a gauge is used to bring the segments ofthe vacuum sleeve into the desired position in relation to the support rods and the coil, and then the metallic components are placed in position on the slots and are soldered in a vacuum tight manner to the segments. Since the metallic components are soldered on, as it were in a floating state," the pressure exerted by the vacuum sleeve on the rod system is not affected by tolerances of the components which are employed. The degree of pressure may be freely adjusted by the selection of the soldering temperature. For this purpose, however, it is necessary that the tube should consist of a plurality of segments which must themselves be supported during the soldering process by means ofa special heat-resistant gauge. Also, the method of floating soldering will, in practice, require vacuum sleeves consisting of materials having high expansion coefficients, and therefore will impose a restriction in respect of the material selection.

SUMMARY OF THE INVENTION In order to achieve a good heat discharge from the delay line without high production costs in a transit time tube of the type described above, and in particular to achieve a reliably high pressure between the delay line and its support rods, which pressure remains uniform over a long period of time, irrespective of the material of the vacuum sleeve, it is proposed, in accordance with the invention, that at least one of the support rods be pressed by at least one ram onto the delay line, which ram extends through a side opening in the tube and is fixed in a vacuum tight manner to the tube.

A transit time tube constructed in accordance with the invention exhibits an arbitrarily adjustable, determinate pressure, unaffected by tolerances in dimensions, between the delay line and its support rods. The vacuum sleeve itself is in one piece, therefore stable, and in addition, when the ram is ground off, exhibits an entirely ridgeless diameter so that it is possible to adapt the tube to the other components of the transit time tube (such as, for example, the sealing components which are to be applied in a vacuum tight manner or the focusing magnet which is to be held radially symmetrically) easily in a shape locking fashion and without taking up an unnecessary amount of space. Fur thermore, as the degree of the soldering temperature is not critical for the desired pressure, it can be set to be such that any solder connections already existing between the individual components cannot be impaired or any solder connections yet to be established between these components can be formed in the same soldering process.

In a preferred exemplary embodiment of the invention, the tube and ram consist of ceramic material. In a particularly simple production process, lateral openings which serve to receive the ram are first bored into the tube, which is already sintered, and the walls of the opening are metallized. Then, the delay line is inserted between support rods which are inserted in the sleeve and fixed to the latter. Subsequently, a further support rod is placed between the delay line and the lateral openings and is pressed onto the delay line by the ram which extends through a lateral opening. The ram is likewise metallized at its periphery in the region of the opening and is subjected to a pressure, such as by weighting, after which it is soldered in a furnace. This will possibly be followed by a process of grinding off the part of the individual rams which project beyond the outer surface of the sleeve.

When ceramic material is employed for the vacuum sleeve and the ram, and the soldering is carried out by heating the vacuum sleeve in a furnace, when the transit time tubecools immediately following the soldering process, the pressure will increase since the delay line, which usually consists of molybdenum, generally has a lower thermal expansion coefficient than ceramic material. On the other hand, the difference between the two expansion coefficients is such that during operation, at the temperature gradients which than usually prevail between the delay line and the sleeve, the delay line expands relatively more greatly than the vacuum sleeve, and thus the bearing pressure increases once again in dependence upon the line load. Therefore, the end result is that the heat discharge increases precisely when necessary.

BRIEF DESCRIPTION OF THE DRAWING Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawing, on which is illustrated a cross sectional view of a delay line supported in a sleeve in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing. a transit time tube constructed in accordance with the invention is illustrated as including a ram which is applied to half the length of the delay line. All the assemblies of a tube which are not essential to the understanding of the invention. for example the magnet system serving to guide the electron beam. or the seals of the vacuum sleeve with the electron beam generator and the electron beam collector, have been omitted for clarity. A coil-shaped or helical delay line I is fixed in position by three cylindrical support rods 2, 3 and 4 which consist of insulating material, such as for example beryllium oxide or diamond. and is surrounded by a vacuum sleeve 5 consisting of ceramic. The vacuum sleeve 5 possesses a side opening 7 through which a ram 6 extends, which ram likewise consists of ceramic. In the exemplary embodiment, the

ram 6 is of a round cross section and is soldered in a vacuum tight fashion to the vacuum sleeve 5 and bears on the support rod 4 at a pressure which is set prior to the soldering process and is maintained during the soldering process, so that a determinate pressure prevails between the coil 5 and its support rods 2, 3 and 4. When a given load is provided during the soldering, the pressure which occurs when the tube has cooled is clearly determined by the soldering temperature on the one hand, and by the thermal expansion coefficients of the individual components on the other hand.

The bearing surface of the ram 6 can be shaped in accordance with the cylindrical surface area of the holding rod 4 in order to provide an intimate contact surface and therefore and improved heat transfer. In order to form good heat bridges, these contact surfaces. and possibly also the contact surfaces between the coil and the support rods. can to particular advantage by soldered to one another or connected in material locking fashion via a suitable metallic intermediate layer, for example a very good heat conducting diluted alloy of copper with a small quantity of beryllium. Techniques for soldering an oxide ceramic to a metal or for the production of an oxide ceramic metal compound via solid body reactions are well known in the art; see. for example. DAS 2,055,657 and DAS 2,116,3l0.

After the ram has been soldered to the vacuum sleeve, the ram may be ground off in such a manner that it does not project beyond the outer surface and the tube can be smoothly inserted into or adapted to a magnet system. Instead, however, in order to further increase the heat discharge, the ram may also be extended through the magnet system and its end positioned, for example, on a radiator.

The invention is not limited to the illustrated exemplary embodiment. Therefore, the transit time tube can also be based on a different coiled type of delay line, for example. a delay line featuring rings and bars. Furthcrmore, neither the number of support rods, nor their cross section, nor the cross section of the vacuum sleeve are specified in any way; the support rods should only extend along the delay line. As a deviation from the described exemplary embodiment, the ram-loaded support rod can also be subjected to a pressure at several points; also in special cases, the support rod and rams may be produced in one piece, in which case a support rod is accommodated in the vacuum sleeve with the rams extending outwardly, and then the coil is introduced into the vacuum sleeve. Finally, it is also possible to use materials other than ceramic. for example metals having a suitable thermal expansion coefficient, for the vacuum sleeve or for the rams.

Although we have described our invention by reference to particular illustrative embodiments thereof. many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore. we intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of our contribution to the art.

We claim:

1. A transit time tube comprising a coil-like delay line. a vacuum sleeve, a plurality of support rods spaced about said delay line and supporting said delay line within said sleeve. at least one opening in said sleeve adjacent one of said support rods, and at least one ram extending through said openings in a sealed relationship with said sleeve and bearing against said one support rod.

2. The tube of claim I, wherein said sleeve and each ram consist of ceramic.

3. The tube of claim I, wherein each ram includes a bearing end surface shaped to conform to the surface of said one support rod.

4. The tube of claim 1, comprising metallic sealing means sealing each ram and said sleeve.

5. The tube of claim 1, wherein said delay line and said one support rod are connected together by solder.

6. The tube of claim 1, wherein the contacts between each ram and said one support rod and said one support rod and said delay line include conforming shaped surface portions.

7. A method of producing a transit time tube, comprising the steps of: forming an opening in the wall of a sleeve; metallizing the surface of the opening; inserting a coil type delay line and a plurality of support rods within the sleeve with one of the support rods adjacent the opening and the rods spaced about the delay line; metallizing a surface portion of a ram; placing the ram through the opening to contact the adjacent support rod with the metallized surfaces adjacent each other; applying pressure to the ram; and placing the structure in a furnace to bond and vacuum seal the ram and sleeve under the applied pressure.

8. The method of claim 7, comprising the step of grinding of the ram after bonding to provide a smooth outer surface of the sleeve. 

1. A transit time tube comprising a coil-like delay line, a vacuum sleeve, a plurality of support rods spaced about said delay line and supporting said delay line within said sleeve, at least one opening in said sleeve adjacent one of said support rods, and at least one ram extending through said openings in a sealed relationship with said sleeve and bearing against said one support rod.
 2. The tube of claim 1, wherein said sleeve and each ram consist of ceramic.
 3. The tube of claim 1, wherein each ram includes a bearing end surface shaped to conform to the surface of said one support rod.
 4. The tube of claim 1, comprising metallic sealing means sealing each ram and said sleeve.
 5. The tube of claim 1, wherein said delay line and said one support rod are connected together by solder.
 6. The tube of claim 1, wherein the contacts between each ram and said one support rod and said one support rod and said delay line include conforming shaped surface portions.
 7. A method of producing a transit time tube, comprising the steps of: forming an opening in the wall of a sleeve; metallizing the surface of the opening; inserting a coil type delay line and a plurality of support rods within the sleeve with one of the support rods adjacent the opening and the rods spaced about the delay line; metallizing a surface portion of a ram; placing the ram through the opening to contact the adjacent support rod with the metallized surfaces adjacent each other; applying pressure to the ram; and placing the structure in a furnace to bond and vacuum seal the ram and sleeve under the applied pressure.
 8. The method of claim 7, comprising the step of grinding of the ram after bonding to provide a smooth outer surface of the sleeve. 